The present invention relates generally to a semiconductor device, and more particularly to a fuse circuit in a semiconductor device with features to ensure the cut status when a fuse is cut.
Semiconductor integrated circuits utilize option processing such as a bonding option, a metal option, and a fuse option for mode switching.
In particular, the fuse option is widely used to replace faulty semiconductor memory cells caused during a fabrication process with normal memory cells and to accommodate to a design change for a semiconductor memory chip modification. In a fuse option, a fuse is cut by irradiating laser beams or flowing an excessive current. A circuit including at least one fuse for the fuse option is referred to as a fuse circuit.
FIG. 1 shows a conventional fuse circuit.
In FIG. 1, the node nd10 of the conventional fuse circuit is precharged to a logic high level in response to a precharge signal FPCG enabled to a logic low level. Then, when the precharge signal FPCG is disabled to a logic high level, first to eighth selection signals SEL<1:8> are inputted, and a level of a latch output signal OUT is determined.
The level of the latch output signal OUT may vary according to the cutting of first to eighth fuses F11-F18. For example, when only the second selection signal SEL<2> among the selection signals SEL<1:8> is inputted at a logic high level, the level of the latch output signal OUT is determined according to the cutting of the second fuse F12. That is, when the second fuse F12 is not cut, the latch output signal OUT is outputted at a logic low level. When the second fuse F12 is cut, the latch output signal OUT is outputted at a logic high level.
In a case where the first to eighth fuses F11-F18 are formed of a material such as copper (Cu), the second fuse F12 cut in the above example is again coupled, causing an error that the latch output signal OUT is outputted at a logic low level. This is because copper ions are moved to fill the cut portion when there is a potential difference between both ends of the first to eighth fuses F11-F18.